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MRI Introduction

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What is MRI?

MRI is a non-invasive method that uses a magnetic field and pulses of radio frequency to image structures and blood flow (functional MRI) in your body. This method allows scientists to image, e.g., bone, brain structure, and changes in brain activity while you are performing various tasks. It is also able to measure the concentration of certain chemical biomarkers inside your body using a technology called a Magnetic Resonance Spectroscopy (MRS).
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Is MRI safe?

To date, over 150 million patients have had MRI examinations. Every year, approximately 10 million patients undergo MRI procedures. MRI has been shown to be extremely safe as long as proper safety precautions are taken. In general, the MRI procedure produces no pain and causes no known short-term or long-term tissue damage of any kind.


Participant Safety Screening

The powerful magnetic field of the scanner can attract certain metallic objects known as “ferromagnetic” objects, causing them to move suddenly and with great force towards the center of the MR system. Therefore, people with any metal implants/fragments and metal eye injury cannot be scanned and should not enter the scanner room. The implants include:

  • Aneurysm clips(s)
  • Cardiac pacemaker
  • Implanted cardioverter defibrillator (ICD)
  • Electronic implant or device
  • Magnetically-activated implant or device
  • Neurostimulation system
  • Spinal cord stimulator
  • Cochlear implant
  • Bone growth/bone fusion stimulator

Other medical or electronic devices in your body may interfere with the MRI examination or potentially pose a risk. UBSN do not recommend people with the following devices/implants undergo the MRI examination. If it is necessary to participate in the MRI examination, please notify the researcher and UBSN staff in advance. UBSN owns the final decision on whether you can participate in the examination. Examples include:

  • Internal electrodes or wires  
  • Otologic, or other ear implant
  • Insulin or other infusion pump
  • Implanted drug infusion device
  • Any type of prosthesis (eye, penile, etc)
  • Heart valve prosthesis
  • Eyelid spring or wire
  • Artificial or prosthetic limb
  • Metallic stent, filter, or coil
  • Shunt (spinal or intraventricular)
  • Vascular access port and/or catheter
  • Radiation seeds or implants
  • Swan-Ganz or thermodilution catheter
  • Medication Patch (Nicotine, Nitroglycerine)
  • Any metallic fragment or foreign body
  • Wire mesh implant
  • Tissue expander (e.g., breast)
  • Surgical staples, clips, or metallic sutures
  • Joint replacement (hip, knee, etc.)
  • Bone/joint pin, screw, nail, wire, plate, etc.
  • IUD, diaphragm, or pessary
  • Dentures or partial plates
  • Tattoo or permanent makeup
  • Body piercing jewelry
  • Hearing aid (Remove before entering MR room)
  • Other implant
Although there is no reason to believe that magnetic resonance imaging harms the fetus, the effects of a strong magnetic field on fetuses have not been fully investigated. For this reason pregnant, or potentially pregnant, women should not participate in the studies.

UBSN also does not allow people who have undergone surgery or tattooing (including make-up tattoos) within the previous six weeks will NOT be scanned under any circumstances. 

For any enquiry, please contact your researchers or UBSN staff (


MRI Preparation

Before you enter the scanner room, please make sure:
  1. Filled in the MRI safety screening form
  2. Signed in the consent form 
  3. No metal or electronic devices in your body 
  4. You are not pregnant
  5. Removed all metallic objects including hearing aid, dentures, partial plates, keys, beeper, cell phone, eyeglasses, hair pins, barrettes, jewellery, watch, safety pins, paperclips, money clip, credit cards, bank cards, magnetic stripe cards, coins, pens, pocket knife, nail clipper, etc. Put personal belongings into the locker.
  6. Changed to patient gown
  7. Changed to MRI-compatible face mask
Please consult MRI operators or researchers if you have any questions or concerns about the MRI examination.


After you enter the scanner room, you will:
  1. be required to use the ear plugs and/or headphones that we supply for use to protect your hearing.
  2. be provided with a squeeze ball. You can squeeze this ball if you want to speak to the operator during the scanning.
  3. lie on the table extending from the MR scanner. An MRI coil will be placed over your head and secured.
  4. be immobilized by brain cushions. For better results, will be asked to hold very still – any movement, especially of your head, will seriously blur the pictures.
  5. be required to avoid crossing your wrists/hands or legs/ankles in order to avoid creating a potential electric current loop.

Although you will be alone in the scanner room, you are allowed to communicate with the researchers and MRI operator during the examination through the intercom system. Please let researchers and MRI operators know immediately, if you feel uncomfortable or wish to terminate the examination for any reason.

You might be required to perform tasks during the scanning. Please refer to your information sheet for more details.


Other Resources

Participants Education Video (Siemens)

Participants Education Poster (Siemens)

Children's Book (Siemens)


Map and Directions


Room ZB216, LG2, Block Z, Phase 8 Building, The Hong Kong Polytechnic University, 181 Chatham Road South, Hung Hom, Kowloon


Tel: 27665384 (Dr. Celia Dong)

Detailed Directions


Campus map_cropped_2

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